文摘
| Figures/TablesFigures/Tables | ReferencesReferences
Summary
Binding of a single-chain Fv antibody to Escherichia coli 尾-galactosidase (尾-gal) is known to stabilize the enzyme and activate several inactive point mutants, historically called antibody-mediated enzyme formation mutants. To understand the nature of this activation, we have determined by electron cryo-microscopy the structure of the complex between 尾-gal and the antibody scFv13R4. Our structure localizes the scFv13R4 binding site to the crevice between domains 1 and 3 in each 尾-gal subunit. The mutations that scFv13R4 counteracts are located between the antibody binding site and the active site of 尾-gal, at one end of the TIM-barrel that forms domain 3 where the substrate lactose is hydrolyzed. The mode of binding suggests how scFv stabilizes both the active site of 尾-gal and the tetrameric state.
